REAL injector sizing, everyone's HP guesses

[walker95svt]

okay, who can tell me what injectors to use? I've read many different articles suggesting different sizes. I don't want to go to big, because I drive my car every day, and it has to have good driveability/idle. They must support a little more than 500 w/ forced induction. here's the mod list:

331 w/a little over 9:1 compression
AFR 185s
paxton novi 2000 with original equipment pulley


I assume this combo will net me 450 at the wheels on a mustang dyno w/ 8-10 lbs of boost. Any guessers what size injectors I'll need? how about hp guesses from guys with similar combos?

 

[final5-0]

By far, most of the power adder combos with those kinds of rwhp use 42's.

Just cruise over to the forum where they all hang out and look at their sigs to see what I talking about.

ProM used to have the formula for inj size but that stuff is now gone.

IIRC the NA formula is .......................

FWHP x .50 then devide by 8

For a power adder the .50 number would have to increase somewhat.

Grady

 

[Grn92LX]

You will easily surpass 500rwhp with that set up. I assume you're doing a good intake, exhaust and cam right? Done right, you're gonna need a low impedence injector I think. You'll need a tune done or a tuning device to make this work. IMO, 42's won't cut it. I know my friends got a simialr combo and run's 65's with a full fuel system.

 

[ponyboy19]

I don't think your 500 rwhp is too far off with 8-10 lbs and a conservative tune up. the 42's will work. Assuming you run 600 FWHP with 52 psi fuel pressure (42 base, + 10 for 1:1 boosted ratio) and a .55 BSFC, 42's will work fine running at 90% duty cycle, which on a bousch injector won't be an issue. 600 fwhp boosted is getting to the limits of a 42 though. but duty cycle and fuel pressure can change things a good bit. Play with this web site and you will see what can and can't be done with them, you can figure out for yourself what you are or aren't comfortable with. If you wanted you could always run some MSD 50's and be done. They are high impedience so you won't need an injector driver or anything. Infact I think you can even get 55 or 60 lb in H-I now. 50's will support 715 fwhp with the parameters I already mentioned and assuming you still run a stock block that is far more then you will ever need. Remember it's better to be over injected than under injected. you can tune out fuel when you get it on the dyno http://www.rceng.com./technical.htm#WORKSHEET

 

[94GTLaserRC]

If you already have 42's, and dont want to upgrade, you could get a Stage 2 Snow Meth Inj kit....I know 2 guys making mid 500s to the wheels with 42's and the kit, and theyre still running slightly rich...When the alcohol is injected under boost, it lowers the fuel requirements, so in the 500hp range, 42's are sufficing.

RC

 

[walker95svt]

lowering boost?

well, I just got a killer deal on a brand new, polished novi 2000 kit. The pulley that comes with it is good for 8-10. I'm sticking with my stock cobra upper and lower (maybe the downs gt-40 upper). The cam is a comp s/c grind, 223-224 dur and 544-560 lift @050. I have all forged internals and dished pistons, but the 2 BOLT BLOCK, because I was a cheapskate. I am not really looking to put out much more than 500 flywheel because of this. I don't always agree with being "over-injected" because of the idling and drivability that comes with massive injectors. A tune is going to be on within days of having the blower on. I'm probably going to schedule the dyno date as soon as my injectors are on the way, and get it tuned by dallas mustang right away. I just wish there was a way to lower the boost from 8-10 until I got a four bolt block in. I've heard it's a bad idea to bring boost below the stock rated level. I'd be happy and secure with 500 flywheel. The block was really well prepared, and has the DSS main support system (whatever that's good for, maybe 1 hp over the stock 2 bolt block rating LOL)

 

[Redsnk95]

42s will be plenty fine for you and will support upwards around 575rwhp.

Troy